Neptunians are a humanoid species from the planet Neptune. Neptunians have pig-like noses, purple skin, and four arms. Their hair is usually black, but can also be dark blue (2ACV13), violet (4ACV09) and brown (4ACV17). Because of their many arms, they are usually masters of coordination and can use all four arms simultaneously. This gives them an edge in terms of multi-tasking and dexterity. The Neptunians make up a fair share of Earth's alien population, and they have their own quarter in New New York, called Little Neptune. Little Neptune has its own foodshops and other stores. Neptunian cooking is quite famous, and is furtherly promoted by the most prominent member of the Neptunian people, Elzar.

Many Neptunians are in the service of Robot Santa Claus, but they are constantly mistreated by him. This forces them to take desperate measures in order to survive. Because Santa doesn't feed them, these Neptunians are a lot smaller than their compatriots on Earth, rendering them of similar proportions to the mythical elves who serve the less homicidal, more traditional Santa.